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  <title>用新值更新旧值</title>
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  <div id="layout-content"><div id="function.apc-cas" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">apc_cas</h1>
  <p class="verinfo">(PECL apc &gt;= 3.1.1)</p><p class="refpurpose"><span class="refname">apc_cas</span> &mdash; <span class="dc-title">用新值更新旧值</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-function.apc-cas-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>apc_cas</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$key</code></span>
   , <span class="methodparam"><span class="type">int</span> <code class="parameter">$old</code></span>
   , <span class="methodparam"><span class="type">int</span> <code class="parameter">$new</code></span>
   ) : <span class="type">bool</span></div>

  <p class="para rdfs-comment">
   <span class="function"><strong>apc_cas()</strong></span> 如果key存在，并且key当前存储的整数等于
   <code class="parameter">old</code>，就使用 
   <code class="parameter">new</code> 更新key当前存储的整数。
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.apc-cas-parameters">
  <h3 class="title">参数</h3>
  <dl>

   
    <dt>
<code class="parameter">key</code></dt>

    <dd>

     <p class="para">
      需要被更新的 key。
     </p>
    </dd>

   
   
    <dt>
<code class="parameter">old</code></dt>

    <dd>

     <p class="para">
      key当前值。
     </p>
    </dd>

   
   
    <dt>
<code class="parameter">new</code></dt>

    <dd>

     <p class="para">
      指定的更新值。
     </p>
    </dd>

   
  </dl>


 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.apc-cas-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-function.apc-cas-examples">
  <h3 class="title">范例</h3>
  <div class="example" id="example-401">
   <p><strong>Example #1 <span class="function"><strong>apc_cas()</strong></span> 示例</strong></p>
   <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />apc_store</span><span style="color: #007700">(</span><span style="color: #DD0000">'foobar'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #DD0000">'$foobar&nbsp;=&nbsp;2'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />echo&nbsp;</span><span style="color: #DD0000">'$foobar&nbsp;==&nbsp;1&nbsp;?&nbsp;2&nbsp;:&nbsp;1&nbsp;=&nbsp;'</span><span style="color: #007700">,&nbsp;(</span><span style="color: #0000BB">apc_cas</span><span style="color: #007700">(</span><span style="color: #DD0000">'foobar'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">)&nbsp;?&nbsp;</span><span style="color: #DD0000">'ok'&nbsp;</span><span style="color: #007700">:&nbsp;</span><span style="color: #DD0000">'fail'</span><span style="color: #007700">),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />echo&nbsp;</span><span style="color: #DD0000">'$foobar&nbsp;==&nbsp;2&nbsp;?&nbsp;1&nbsp;:&nbsp;2&nbsp;=&nbsp;'</span><span style="color: #007700">,&nbsp;(</span><span style="color: #0000BB">apc_cas</span><span style="color: #007700">(</span><span style="color: #DD0000">'foobar'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">)&nbsp;?&nbsp;</span><span style="color: #DD0000">'ok'&nbsp;</span><span style="color: #007700">:&nbsp;</span><span style="color: #DD0000">'fail'</span><span style="color: #007700">),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /><br />echo&nbsp;</span><span style="color: #DD0000">'$foobar&nbsp;=&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">apc_fetch</span><span style="color: #007700">(</span><span style="color: #DD0000">'foobar'</span><span style="color: #007700">),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /><br />echo&nbsp;</span><span style="color: #DD0000">'$f__bar&nbsp;==&nbsp;1&nbsp;?&nbsp;2&nbsp;:&nbsp;1&nbsp;=&nbsp;'</span><span style="color: #007700">,&nbsp;(</span><span style="color: #0000BB">apc_cas</span><span style="color: #007700">(</span><span style="color: #DD0000">'f__bar'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">)&nbsp;?&nbsp;</span><span style="color: #DD0000">'ok'&nbsp;</span><span style="color: #007700">:&nbsp;</span><span style="color: #DD0000">'fail'</span><span style="color: #007700">),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">apc_store</span><span style="color: #007700">(</span><span style="color: #DD0000">'perfection'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'xyz'</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #DD0000">'$perfection&nbsp;==&nbsp;2&nbsp;?&nbsp;1&nbsp;:&nbsp;2&nbsp;=&nbsp;'</span><span style="color: #007700">,&nbsp;(</span><span style="color: #0000BB">apc_cas</span><span style="color: #007700">(</span><span style="color: #DD0000">'perfection'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">)&nbsp;?&nbsp;</span><span style="color: #DD0000">'ok'&nbsp;</span><span style="color: #007700">:&nbsp;</span><span style="color: #DD0000">'epic&nbsp;fail'</span><span style="color: #007700">),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /><br />echo&nbsp;</span><span style="color: #DD0000">'$foobar&nbsp;=&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">apc_fetch</span><span style="color: #007700">(</span><span style="color: #DD0000">'foobar'</span><span style="color: #007700">),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
   </div>

   <div class="example-contents"><p>以上例程的输出类似于：</p></div>
   <div class="example-contents screen">
<div class="cdata"><pre>
$foobar = 2
$foobar == 1 ? 2 : 1 = fail
$foobar == 2 ? 1 : 2 = ok
$foobar = 1
$f__bar == 1 ? 2 : 1 = fail
$perfection == 2 ? 1 : 2 = epic fail
$foobar = 1
</pre></div>
   </div>
  </div>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.apc-cas-seealso">
  <h3 class="title">参见</h3>
  <ul class="simplelist">
   <li class="member"><span class="function"><a href="apc_dec.html" class="function" rel="rdfs-seeAlso">apc_dec()</a> - Decrease a stored number</span></li>
   <li class="member"><span class="function"><a href="apc_store.html" class="function" rel="rdfs-seeAlso">apc_store()</a> - Cache a variable in the data store</span></li>
  </ul>
 </div>


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